samedi 18 août 2012

The scientists and engineers of NASA's Curiosity rover mission have selected the first driving destination for their one-ton, six-wheeled mobile Mars laboratory. The target area, named Glenelg, is a natural intersection of three kinds of terrain. The choice was described by Curiosity Project Scientist John Grotzinger of the California Institute of Technology during a media teleconference on Aug. 17.

"With such a great landing spot in Gale Crater, we literally had every degree of the compass to choose from for our first drive," Grotzinger said. "We had a bunch of strong contenders. It is the kind of dilemma planetary scientists dream of, but you can only go one place for the first drilling for a rock sample on Mars. That first drilling will be a huge moment in the history of Mars exploration."

This image shows the landing site of NASA's Curiosity rover and destinations scientists want to investigate. Image credit: NASA/JPL-Caltech/Univ. of Arizona.

The trek to Glenelg will send the rover 1,300 feet (400 meters) east-southeast of its landing site. One of the three types of terrain intersecting at Glenelg is layered bedrock, which is attractive as the first drilling target.

"We're about ready to load our new destination into our GPS and head out onto the open road," Grotzinger said. "Our challenge is there is no GPS on Mars, so we have a roomful of rover-driver engineers providing our turn-by-turn navigation for us."

Image above: Still Life with Rover - This full-resolution self-portrait shows the deck of NASA's Curiosity rover from the rover's Navigation camera. The back of the rover can be seen at the top left of the image, and two of the rover's right side wheels can be seen on the left. The undulating rim of Gale Crater forms the lighter color strip in the background. Bits of gravel, about 0.4 inches (1 centimeter) in size, are visible on the deck of the rover. Image credit: NASA/JPL-Caltech.

Prior to the rover's trip to Glenelg, the team in charge of Curiosity's Chemistry and Camera instrument, or ChemCam, is planning to give their mast-mounted, rock-zapping laser and telescope combination a thorough checkout. On Saturday night, Aug. 18, ChemCam is expected to "zap" its first rock in the name of planetary science. It will be the first time such a powerful laser has been used on the surface of another world.

Curiosity ready to Drive. Image credit: NASA/JPL-Caltech

"Rock N165 looks like your typical Mars rock, about three inches wide. It's about 10 feet away," said Roger Wiens, principal investigator of the ChemCam instrument from the Los Alamos National Laboratory in New Mexico. "We are going to hit it with 14 millijoules of energy 30 times in 10 seconds. It is not only going to be an excellent test of our system, it should be pretty cool too."

Mission engineers are devoting more time to planning the first roll of Curiosity. In the coming days, the rover will exercise each of its four steerable (front and back) wheels, turning each of them side-to-side before ending up with each wheel pointing straight ahead. On a later day, the rover will drive forward about one rover-length (10 feet, or 3 meters), turn 90 degrees, and then kick into reverse for about 7 feet (2 meters).

Image above: Glenelg Intrigue - This image shows a closer view of the landing site of NASA's Curiosity rover and a destination nearby known as Glenelg. Curiosity landed inside Gale Crater on Mars on Aug. 5 PDT (Aug. 6 EDT) at the blue dot. It is planning on driving to an area marked with a red dot that is nicknamed Glenelg. That area marks the intersection of three kinds of terrain. Starting clockwise from the top of this image, scientists are interested in this brighter terrain because it may represent a kind of bedrock suitable for eventual drilling by Curiosity. The next terrain shows the marks of many small craters and intrigues scientists because it might represent an older or harder surface. The third, which is the kind of terrain Curiosity landed in, is interesting because scientists can try to determine if the same kind of rock texture at Goulburn, an area where blasts from the descent stage rocket engines scoured away some of the surface, also occurs at Glenelg. Image credit: NASA/JPL-Caltech/Univ. of Arizona.

"There will be a lot of important firsts that will be taking place for Curiosity over the next few weeks, but the first motion of its wheels, the first time our roving laboratory on Mars does some actual roving, that will be something special," said Michael Watkins, mission manager for Curiosity from the Jet Propulsion Laboratory in Pasadena, Calif.

The Mars Science Laboratory spacecraft delivered Curiosity to its target area on Mars at 10:31:45 p.m. PDT on Aug. 5 (1:31:45 a.m. EDT on Aug. 6), which included the 13.8 minutes needed for confirmation of the touchdown to be radioed to Earth at the speed of light.

The mission is managed by JPL for NASA's Science Mission Directorate in Washington. The rover was designed, developed and assembled at JPL, a division of Caltech. ChemCam was provided by Los Alamos National Laboratory. France provided ChemCam's laser and telescope.

vendredi 17 août 2012

This is a Hubble Space Telescope image of a pair of star clusters that are believed to be in the early stages of merging. The clusters lie in the gigantic 30 Doradus nebula, which is 170,000 light-years from Earth. The Hubble observations, made with the Wide Field Camera 3, were taken Oct. 20-27, 2009. The blue color is light from the hottest, most massive stars; the green from the glow of oxygen; and the red from fluorescing hydrogen. Image Credit: NASA, ESA, R. O'Connell (University of Virginia), and the Wide Field Camera 3 Science Oversight Committee

Astronomers using data from NASA's Hubble Space Telescope have caught two clusters full of massive stars that may be in the early stages of merging. The clusters are 170,000 light-years away in the Large Magellanic Cloud, a small satellite galaxy to our Milky Way.

What at first was thought to be only one cluster in the core of the massive star-forming region 30 Doradus (also known as the Tarantula Nebula) has been found to be a composite of two clusters that differ in age by about one million years.

The entire 30 Doradus complex has been an active star-forming region for 25 million years, and it is currently unknown how much longer this region can continue creating new stars. Smaller systems that merge into larger ones could help to explain the origin of some of the largest known star clusters.

Lead scientist Elena Sabbi of the Space Telescope Science Institute in Baltimore, Md., and her team began looking at the area while searching for runaway stars, fast-moving stars that have been kicked out of their stellar nurseries where they first formed. "Stars are supposed to form in clusters, but there are many young stars outside 30 Doradus that could not have formed where they are; they may have been ejected at very high velocity from 30 Doradus itself," Sabbi said.

She then noticed something unusual about the cluster when looking at the distribution of the low-mass stars detected by Hubble. It is not spherical, as was expected, but has features somewhat similar to the shape of two merging galaxies where their shapes are elongated by the tidal pull of gravity. Hubble’s circumstantial evidence for the impending merger comes from seeing an elongated structure in one of the clusters, and from measuring a different age between the two clusters.

According to some models, the giant gas clouds out of which star clusters form may fragment into smaller pieces. Once these small pieces precipitate stars, they might then interact and merge to become a bigger system. This interaction is what Sabbi and her team think they are observing in 30 Doradus.

Hubble Space Telescope

Also, there are an unusually large number of high-velocity stars around 30 Doradus. Astronomers believe that these stars, often called "runaway stars" were expelled from the core of 30 Doradus as the result of dynamical interactions. These interactions are very common during a process called core collapse, in which more-massive stars sink to the center of a cluster by dynamical interactions with lower-mass stars. When many massive stars have reached the core, the core becomes unstable and these massive stars start ejecting each other from the cluster.

The big cluster R136 in the center of the 30 Doradus region is too young to have already experienced a core collapse. However, since in smaller systems the core collapse is much faster, the large number of runaway stars that has been found in the 30 Doradus region can be better explained if a small cluster has merged into R136.

Follow-up studies will look at the area in more detail and on a larger scale to see if any more clusters might be interacting with the ones observed. In particular, the infrared sensitivity of NASA’s planned James Webb Space Telescope (JWST) will allow astronomers to look deep into the regions of the Tarantula Nebula that are obscured in visible-light photographs. In these areas cooler and dimmer stars are hidden from view inside cocoons of dust. Webb will better reveal the underlying population of stars in the nebula.

The 30 Doradus Nebula is particularly interesting to astronomers because it is a good example of how star-forming regions in the young universe may have looked. This discovery could help scientists understand the details of cluster formation and how stars formed in the early universe.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Md., conducts Hubble science operations. STScI is operated by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

Saturn's moon Mimas peeps out from behind the larger moon Dione in this view from the Cassini spacecraft.

Mimas (246 miles, or 396 kilometers across) is near the bottom center of the image. Saturn's rings are also visible in the top right.

This view looks toward the anti-Saturn side of Dione (698 miles, or 1,123 kilometers across). North on Dione is up and rotated 20 degrees to the right. This view looks toward the northern, sunlit side of the rings from just above the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Dec. 12, 2011. The view was obtained at a distance of approximately 377,000 miles (606,000 kilometers) from Mimas. The view was obtained at a distance of approximately 56,000 miles (91,000 kilometers) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 42 degrees. Image scale is 1,773 feet (541 meters) per pixel on Dione.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

NASA's Advanced Composition Explorer (ACE) observes a wide array of particles that flow toward Earth from the sun to better understand the great space weather system that connects the sun to our planet. Credit: NASA/H. Zell.

In the quest to understand how the world's weather moves around the globe, scientists have had to tease apart different kinds of atmospheric movement, such as the great jet streams that can move across a whole hemisphere versus more intricate, localized flows. Much the same must currently be done to understand the various motions at work in the great space weather system that links the sun and Earth as the sun shoots material out in all directions, creating its own version of a particle sea to fill up the solar system.

"People think of the sun as giving out light and heat," says Ruth Skoug, a space scientist at Los Alamos National Laboratory in Los Alamos, N.M. "But it is also always losing particles, losing mass."

For example, the sun sends out a steady outflow of solar particles called the solar wind and additionally giant, sudden explosions of material called coronal mass ejections or CMEs erupt out into space. Skoug studies a third kind of particle flow: jets of high-energy electrons streaming from the sun known as electron strahl. Through a new five-year study of observations of the strahl, Skoug and her colleagues have researched another piece of this giant space weather puzzle around Earth.

Skoug says that each fast-moving electron is by and large constrained to move along magnetic field lines that flow out from the sun, some of which loop back to touch the sun again, others which extend out to the edges of the solar system. The charge on an electron interacts with the field lines such that each particle sticks close to the line, somewhat like a bead on an abacus – with the added motion that the electron gyrates in circles around the field lines at the same time.

In general, the magnetic fields get weaker further away from the sun. A physical law that applies in those cases in which electrons are not pushed off course, or “scattered,” demands that the electron gyrations get smaller and more stretched out along the field line. If this were the only physics at work, therefore, one would expect the strahl to become a more and more focused, pencil-thin beam when measured near Earth. This measurement is done by NASA's Advanced Composition Explorer (ACE) mission, but it shows that the expected focusing doesn’t quite happen.

"Wherever we look, the electron strahl is much wider than we would have expected," says Eric Christian, the NASA's deputy project scientist for ACE at NASA Goddard Space Flight Center in Greenbelt, Md. "So there must be some process that helps scatter the electrons into a wider beam."

Indeed, the strahls come in a wide variety of sizes, so Skoug and her colleagues sifted through five years worth of ACE data to see if they could find any patterns. While they spotted strahls of all widths, they did find that certain sizes showed up more frequently. They also found that strahls along open field lines, those that do not return to the sun, have different characteristics than those on closed field lines, those that do return to the sun. On the open field lines, the most common width by far is about ten times the size of the thin beam of electrons expected if there had been no extra scattering. The closed field lines, however, showed a nearly equal number of strahls at that width and at a width some four times even larger.

The strahls on the closed field lines showed an additional pattern. While the strahls might differ in width, they did not tend to differ in the total number of electrons passing by. This suggests that the different shaped strahls – which often come from similar places on the sun -- may have been the same in composition when they left the sun, but were altered by the path they traveled and scattering they encountered along their journey.

While each piece of statistical information like this may seem slightly esoteric, together they help constrain what kinds of scattering might be at work in space.

"We don't yet know how the electrons get scattered into these different widths," says Skoug. "The electrons are so spread out that they rarely bump into each other to get pushed off course, so instead we think that electromagnetic waves add energy, and therefore speed, to the particles."

There are numerous types of these waves, however, traveling at different speeds, in different sizes and in different directions, and no one yet knows which kinds of waves might be at work. Research like this helps start the process of eliminating certain scattering options, since the correct version must, of course, cause the specific variations seen by Skoug and her colleagues.

jeudi 16 août 2012

This color-enhanced view of NASA's Curiosity rover on the surface of Mars was taken by the High Resolution Imaging Science Experiment (HiRISE) on NASA's Mars Reconnaissance Orbiter as the satellite flew overhead. Image credit: NASA/JPL-Caltech/University of Arizona.

The first color image taken from orbit showing NASA's rover Curiosity on Mars includes details of the layered bedrock on the floor of Gale Crater that the rover is beginning to investigate.

Operators of the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter added the color view to earlier observations of Curiosity descending on its parachute, and one day after landing.

"The rover appears as double bright spot plus shadows from this perspective, looking at its shadowed side, set in the middle of the blast pattern from the descent stage," said HiRISE Principal Investigator Alfred McEwen, of the University of Arizona, Tucson. "This image was acquired from an angle looking 30 degrees westward of straight down. We plan to get one in a few days looking more directly down, showing the rover in more detail and completing a stereo pair."

Meanwhile, Curiosity has finished a four-day process transitioning both of its redundant main computers to flight software for driving and using tools on the rover's arm. During the latter part of the Mars Science Laboratory spacecraft's 36-week flight to Mars and its complicated descent to deliver Curiosity to the Martian surface on Aug. 5, PDT (Aug. 6, EDT and Universal Time), the rover's computers used a version of flight software with many capabilities no longer needed. The new version expands capabilities for work the rover will do now that it is on Mars.

"We have successfully completed the brain transplant," said Curiosity Mission Manager Mike Watkins of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "Now we are moving on to a new phase of functional checkouts of the science instruments and preparations for a short test drive."

The first drive, possibly within a week or so, will likely include short forward and reverse segments and a turn. Curiosity has a separate drive motor on each of its six wheels and steering motors on the four corner wheels. Preparation and testing of the motor controllers will precede the first drive.

After the test drive, the planning schedule has an "intermission" before a second testing phase focused on use of the rover's robotic arm. For the intermission, the 400-member science team will have the opportunity to pick a location for Curiosity to drive to before the arm-testing weeks.

Mars Reconnaissance Orbiter (MRO). Image credit: NASA/JPL-Caltech

"It's fair to say that the scientists, not to mention the rover drivers, are itching to move," said JPL's Ashwin Vasavada, deputy project scientist for Curiosity.

Researchers have been examining images from Curiosity's cameras and HiRISE to identify potential targets to investigate near the rover and on the visible slope of the nearby three-mile-high mound informally named Mount Sharp.

"The science and operations teams are evaluating several potential routes that would take us to Mount Sharp, with perhaps a few waypoints to inspect some of the different terrains we've identified as we map the landing area," Vasavada said. "As we have reported many times before, it's going to take us a good part of our first year to make it to the layered sediments on Mount Sharp."

During a prime mission of nearly two years, researchers will use Curiosity to investigate whether the selected area of Mars has ever offered chemical ingredients for life and other environmental conditions favorable for supporting microbial life. Curiosity carries 10 science instruments with a total mass 15 times as large as the science payloads on NASA's Mars rovers Spirit and Opportunity.

To handle this science toolkit, Curiosity is twice as long and five times as heavy as Spirit or Opportunity. The landing site inside Gale Crater places the rover within driving distance of layers of Mount Sharp. Observations from orbit have identified clay and sulfate minerals in the lower layers, indicating a wet history.

JPL, a division of the California Institute of Technology, in Pasadena, manages the Mars Science Laboratory and Mars Reconnaissance Orbiter missions for NASA's Science Mission Directorate, Washington. JPL designed and built Curiosity. HiRISE is operated by the University of Arizona in Tucson. The instrument was built by Ball Aerospace & Technologies Corp. in Boulder, Colo. Lockheed Martin Space Systems in Denver built the orbiter.

mercredi 15 août 2012

Astronomers have found an extraordinary galaxy cluster, one of the largest objects in the universe, that is breaking several important cosmic records. Observations of the Phoenix cluster with NASA's Chandra X-ray Observatory, the National Science Foundation's South Pole Telescope, and eight other world-class observatories may force astronomers to rethink how these colossal structures and the galaxies that inhabit them evolve.

Stars are forming in the Phoenix cluster at the highest rate ever observed for the middle of a galaxy cluster. The object also is the most powerful producer of X-rays of any known cluster and among the most massive. The data also suggest the rate of hot gas cooling in the central regions of the cluster is the largest ever observed.

The Phoenix cluster is located about 5.7 billion light years from Earth. It is named not only for the constellation in which it is located, but also for its remarkable properties.

"While galaxies at the center of most clusters may have been dormant for billions of years, the central galaxy in this cluster seems to have come back to life with a new burst of star formation," said Michael McDonald, a Hubble Fellow at the Massachusetts Institute of Technology and the lead author of a paper appearing in the Aug. 16 issue of the journal Nature. "The mythology of the Phoenix, a bird rising from the dead, is a great way to describe this revived object."

(Click on the image for enlarge)

Image above: The hot gas in Phoenix is giving off copious amounts of X-rays and cooling quickly over time, especially near the center of the cluster, causing gas to flow inwards and form huge numbers of stars. These features are shown in this artist's impression of the central galaxy, with hot gas shown in red, cooler gas shown in blue, the gas flows shown by the ribbon-like features and the newly formed stars in blue. (NASA/CXC/M.Weiss).

Like other galaxy clusters, Phoenix contains a vast reservoir of hot gas, which itself holds more normal matter -- not dark matter -- than all of the galaxies in the cluster combined. This reservoir can be detected only with X-ray telescopes such as Chandra. The prevailing wisdom once had been that this hot gas should cool over time and sink to the galaxy at the center of the cluster, forming huge numbers of stars. However, most galaxy clusters have formed very few stars during the last few billion years. Astronomers think the supermassive black hole in the central galaxy of a cluster pumps energy into the system, preventing cooling of gas from causing a burst of star formation.

The famous Perseus cluster is an example of a black hole bellowing out energy and preventing the gas from cooling to form stars at a high rate. Repeated outbursts in the form of powerful jets from the black hole in the center of Perseus created giant cavities and produced sound waves with an incredibly deep B-flat note 57 octaves below middle C, which, in turn, keeps the gas hot.

Animation of the Phoenix Cluster

"We thought that these very deep sounds might be found in galaxy clusters everywhere," said co-author Ryan Foley, a Clay Fellow at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. "The Phoenix cluster is showing us this is not the case -- or at least there are times the music essentially stops. Jets from the giant black hole at the center of a cluster are apparently not powerful enough to prevent the cluster gas from cooling."

With its black hole not producing powerful enough jets, the center of the Phoenix cluster is buzzing with stars that are forming about 20 times faster than in the Perseus cluster. This rate is the highest seen in the center of a galaxy cluster but not the highest seen anywhere in the universe. However, other areas with the highest star formation rates, located outside clusters, have rates only about twice as high.

The frenetic pace of star birth and cooling of gas in the Phoenix cluster are causing the galaxy and the black hole to add mass very quickly -- an important phase the researchers predict will be relatively short-lived.

"The galaxy and its black hole are undergoing unsustainable growth," said co-author Bradford Benson, of the University of Chicago. "This growth spurt can't last longer than about a hundred million years. Otherwise, the galaxy and black hole would become much bigger than their counterparts in the nearby universe."

Remarkably, the Phoenix cluster and its central galaxy and supermassive black hole are already among the most massive known objects of their type. Because of their tremendous size, galaxy clusters are crucial objects for studying cosmology and galaxy evolution, so finding one with such extreme properties like the Phoenix cluster is important.

"This spectacular star burst is a very significant discovery because it suggests we have to rethink how the massive galaxies in the centers of clusters grow," said Martin Rees of Cambridge University, a world-renowned expert on cosmology who was not involved with the study. "The cooling of hot gas might be a much more important source of stars than previously thought."

The Phoenix cluster originally was detected by the National Science Foundation's South Pole Telescope, and later was observed in optical light by the Gemini Observatory, the Blanco 4-meter telescope and Magellan telescope, all in Chile. The hot gas and its rate of cooling were estimated from Chandra data. To measure the star formation rate in the Phoenix cluster, several space-based telescopes were used, including NASA's Wide-field Infrared Survey Explorer and Galaxy Evolution Explorer and ESA's Herschel.

Just as René Magritte wrote “This is not a pipe” on his famous painting, this is also not a pipe. It is however a picture of part of a vast dark cloud of interstellar dust called the Pipe Nebula. This new and very detailed image of what is also known as Barnard 59 was captured by the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory. By coincidence this image is appearing on the 45th anniversary of the painter’s death.

The Pipe Nebula is a prime example of a dark nebula. Originally, astronomers believed these were areas in space where there were no stars. But it was later discovered that dark nebulae actually consist of clouds of interstellar dust so thick it can block out the light from the stars beyond. The Pipe Nebula appears silhouetted against the rich star clouds close to the centre of the Milky Way in the constellation of Ophiuchus (The Serpent Bearer).

Barnard 59, a dark nebula in the constellation of Ophiuchus

Barnard 59 forms the mouthpiece of the Pipe Nebula [1] and is the subject of this new image from the Wide Field Imager on the MPG/ESO 2.2-metre telescope. This strange and complex dark nebula lies about 600–700 light-years away from Earth.

The nebula is named after the American astronomer Edward Emerson Barnard who was the first to systematically record dark nebulae using long-exposure photography and one of those who recognised their dusty nature. Barnard catalogued a total of 370 dark nebulae all over the sky. A self-made man, he bought his first house with the prize money from discovering several comets. Barnard was an extraordinary observer with exceptional eyesight who made contributions in many fields of astronomy in the late 19th and early 20th century.

Zooming in on the dark nebula Barnard 59

At first glance, your attention is most likely drawn to the centre of the image where dark twisting clouds look a little like the legs of a vast spider stretched across a web of stars. However, after a few moments you will begin to notice several finer details. Foggy, smoky shapes in the middle of the darkness are lit up by new stars that are forming. Star formation is common within regions that contain dense, molecular clouds, such as in dark nebulae. The dust and gas will clump together under the influence of gravity and more and more material will be attracted until the star is formed. However, compared to similar regions, the Barnard 59 region is undergoing relatively little star formation and still has a great deal of dust.

If you look carefully you may also be able to spot more than a dozen tiny blue, green and red strips scattered across the picture. These are asteroids, chunks of rock and metal a few kilometres across that are orbiting the Sun. The majority lie in the asteroid belt between the orbits of Mars and Jupiter. Barnard 59 is about ten million times further away from the Earth than these tiny objects [2].

Panning across the dark nebula Barnard 59

And finally, as you take in this richly textured tapestry of celestial objects, consider for a moment that when you look up at this region of sky from Earth you would be able to fit this entire image under your thumb held at arms-length despite it being about six light-years across at the distance of Barnard 59.

Notes:

[1] The entire Pipe Nebula is comprised of Barnard 65, 66, 67 and 78, in addition to Barnard 59. It can be seen easily with the unaided eye under dark and clear skies and is best spotted from southern latitudes where it appears higher in the sky.

[2] Asteroids move during the exposures and create short trails. As this picture was created from several images taken in different colours at different times the different colour trails are also shifted relative to each other.

More information:

The year 2012 marks the 50th anniversary of the founding of the European Southern Observatory (ESO). ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 40-metre-class European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

mardi 14 août 2012

Curiosity has done the "brain transplant" needed to optimize it for surface operations, and is checking the instruments it will use to explore Mars.

The mission team is also looking down from orbit at Curiosity's new home in Gale Crater, seen in the updated landing graphic at left, with the green dot showing the rover's landing spot.

New images from the Curiosity rover mission have been released as part of a NASA teleconference that took place on Tuesday, Aug. 14, 2012, to provide a status update on the mission to Mars’ Gale Crater.

A Whole New World for Curiosity

This color-enhanced view -- taken by the High Resolution Imaging Science Experiment (HiRISE) on NASA's Mars Reconnaissance Orbiter as the satellite flew overhead -- shows the terrain around the rover's landing site within Gale Crater on Mars. Colors were enhanced to bring out subtle differences, showing that the landing region is not as colorful as regions to the south, closer to Mount Sharp, where Curiosity will eventually explore. In reality, the blue colors are more gray.

The rover itself is seen as the circular object, with the blast pattern from its descent stage seen as relatively blue colors. The dark dune fields lying between the rover and Mount Sharp can be seen in the lower portion of the picture. Mount Sharp is out of view, below the image frame. The rover is about 980 feet (300 meters) from the bottom of the picture.

This image was acquired six days after Curiosity landed at an angle of 30 degrees from straight down, looking west. Another image looking more directly down will be acquired in five days, completing a stereo pair along with this image. The scale of this image cutout is about 24 inches (62 centimeter) per pixel.

HiRISE is one of six instruments on NASA's Mars Reconnaissance Orbiter. The University of Arizona, Tucson, operates the orbiter's HiRISE camera, which was built by Ball Aerospace & Technologies Corp., Boulder, Colo. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter Project for NASA’s Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, built the spacecraft. Image credit: NASA/JPL-Caltech/University of Arizona.

Curiosity in Exaggerated Color

This color-enhanced view of NASA's Curiosity rover on the surface of Mars was taken by the High Resolution Imaging Science Experiment (HiRISE) on NASA's Mars Reconnaissance Orbiter as the satellite flew overhead. Colors have been enhanced to show the subtle color variations near the rover, which result from different types of materials.

The descent stage blast pattern around the rover is clearly seen as relatively blue colors (true colors would be more gray). Curiosity landed within Gale Crater, a portion of which is pictured here. The mountain at the center of the crater, called Mount Sharp, is located out of frame to the southeast. North is up.

This image was acquired at an angle of 30 degrees from straight down, looking west. Another image looking more directly down will be acquired in five days, completing a stereo pair along with this image. The scale of this image cutout is about 12 inches (31 centimeters) per pixel.

HiRISE is one of six instruments on NASA's Mars Reconnaissance Orbiter. The University of Arizona, Tucson, operates the orbiter's HiRISE camera, which was built by Ball Aerospace & Technologies Corp., Boulder, Colo. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter Project for NASA’s Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, built the spacecraft. Image credit: NASNASA/JPL-Caltech/University of Arizona.

Curiosity Cradled by Gale Crater (click on the image for enlarge)

NASA's Curiosity rover landed in the Martian crater known as Gale Crater, which is approximately the size of Connecticut and Rhode Island combined. A green dot shows where the rover landed, well within its targeted landing ellipse, outlined in blue.

This oblique view of Gale, and Mount Sharp in the center, is derived from a combination of elevation and imaging data from three Mars orbiters. The view is looking toward the southeast. Mount Sharp rises about 3.4 miles (5.5 kilometers) above the floor of Gale Crater.

The image combines elevation data from the High Resolution Stereo Camera on the European Space Agency's Mars Express orbiter, image data from the Context Camera on NASA's Mars Reconnaissance Orbiter, and color information from Viking Orbiter imagery. There is no vertical exaggeration in the image. Image credit: NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS.

Crisp View from Inside Gale Crater (click on the image for enlarge)

This 360-degree, full-resolution panorama from NASA's Curiosity rover shows the area all around the rover within Gale Crater on Mars. The rover's deck is to the left and far right. The rover's "head" or mast, where the Navigation cameras that took this picture are located, casts a shadow seen near the center. The rim of Gale Crater is to the left, and the base of Mount Sharp is to the center-right. The summit of Mount Sharp will be imaged at a later time.

Curiosity will drive to the knolls of layered rock at the lower slopes of Mount Sharp to investigate their history and geology in detail. That destination is to the south-southwest, beyond the dark sand dunes. In the annotated version of this image, degrees are listed at the very top. North is at zero degrees, to the left, and the south-southwest is to the middle-right at 193 degrees. Image credit: NASA/JPL-Caltech.

Destination Mount Sharp

This image from NASA's Curiosity rover looks south of the rover's landing site on Mars towards Mount Sharp. This is part of a larger,high-resolution color mosaic made from images obtained by Curiosity's Mast Camera.

In this version of the image, colors have been modified as if the scene were transported to Earth and illuminated by terrestrial sunlight. This processing, called "white balancing," is useful for scientists to be able to recognize and distinguish rocks by color in more familiar lighting.

The image provides an overview of the eventual geological targets Curiosity will explore over the next two years, starting with the rock-strewn, gravelly surface close by, and extending towards the dark dunefield. Beyond that lie the layered buttes and mesas of the sedimentary rock of Mount Sharp.

The images in this mosaic were acquired by the 34-millimeter Mastcam over about an hour of time on Aug. 8, 2012 PDT (Aug. 9, 2012 EDT), each at 1,200 by 1,200 pixels in size. Image credit: NASA/JPL-Caltech/MSSS.

LHC experiments bring new insight into matter of the primordial universe

Experiments using heavy ions at CERN’s (1*) Large Hadron Collider (LHC) are advancing understanding of the primordial universe. The ALICE, ATLAS and CMS collaborations have made new measurements of the kind of matter that probably existed in the first instants of the universe. They will present their latest results at the Quark Matter 2012 conference, which starts today in Washington DC. The new findings are based mainly on the four-week LHC run with lead ions in 2011, during which the experiments collected 20 times more data than in 2010.

Just after the big bang, quarks and gluons – basic building blocks of matter – were not confined inside composite particles such as protons and neutrons, as they are today. Instead, they moved freely in a state of matter known as "quark–gluon plasma". Collisions of lead ions in the LHC, the world’s most powerful particle accelerator, recreate for a fleeting moment conditions similar to those of the early universe. By examining a billion or so of these collisions, the experiments have been able to make more precise measurements of the properties of matter under these extreme conditions.

“The field of heavy-ion physics is crucial for probing the properties of matter in the primordial universe, one of the key questions of fundamental physics that the LHC and its experiments are designed to address. It illustrates how in addition to the investigation of the recently discovered Higgs-like boson, physicists at the LHC are studying many other important phenomena in both proton–proton and lead–lead collisions,” said CERN Director-General Rolf Heuer.

At the conference, the ALICE, ATLAS and CMS collaborations will present more refined characterizations of the densest and hottest matter ever studied in the laboratory – 100,000 times hotter than the interior of the Sun and denser than a neutron star.

Heavy-ion collision recorded by ALICE in 2011 (Image: CERN)

ALICE will present a wealth of new results on all aspects of the evolution of high-density, strongly interacting matter in both space and time. Important studies deal with “charmed particles”, which contain a charm or anticharm quark. Charm quarks, 100 times heavier than the up and down quarks that form normal matter, are significantly decelerated by their passage through quark–gluon plasma, offering scientists a unique tool to probe its properties. ALICE physicists will report indications that the flow in the plasma is so strong that the heavy charmed particles are dragged along by it. The experiment has also observed indications of a thermalization phenomenon, which involves the recombination of charm and anticharm quarks to form “charmonium”.

“This is only one leading example of the scientific opportunities in reach of the ALICE experiment,” said Paolo Giubellino, spokesperson of the ALICE collaboration. “With more data still being analysed and further data-taking scheduled for next February, we are closer than ever to unravelling the properties of the primordial state of the universe: the quark–gluon plasma.”

In the 1980s, the initial dissociation of charmonium was proposed as a direct signature for the formation of quark–gluon plasma, and first experimental indications of this dissociation were reported from fixed-target experiments at CERN’s Super Proton Synchrotron in 2000. The much higher energy of the LHC makes it possible for the first time to study similar tightly-bound states of the heavier beauty quarks. The hypothesis was that, depending on their binding energy, some of these states would “melt” in the plasma produced, while others would survive the extreme temperature. The CMS experiment now observes clear signs of the expected sequential suppression of the “quarkonium” (quark–antiquark) states.

“CMS will present important new heavy-ion results not only on quarkonium suppression, but also on bulk properties of the medium and on a variety of studies of jet quenching,” said CMS spokesperson Joseph Incandela. “We are entering an exciting new era of high-precision research on strongly interacting matter at the highest energies produced in the laboratory.”

CERN - LHC

The quenching of jets is the phenomenon in which highly energetic sprays of particles break up in the dense quark–gluon plasma, giving scientists detailed information about the density and properties of the produced matter. ATLAS will report new findings on jet quenching, including a high-precision study of how the jets fragment in matter, and on the correlations between jets and electroweak bosons. The results are complementary to other exciting ones, including groundbreaking findings on the flow of the plasma.

“We have entered a new phase in which we not only observe the phenomenon of quark–gluon plasma, but where we can also make high-precision measurements using a variety of probes,” said ATLAS spokesperson Fabiola Gianotti. “The studies will contribute significantly to our understanding of the early universe.”

Note:

1*.CERN, the European Organization for Nuclear Research, is the world's leading laboratory for particle physics. It has its headquarters in Geneva. At present, its member states are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, the Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. Romania is a candidate for accession. Israel and Serbia are associate members in the pre-stage to membership. India, Japan, the Russian Federation, the United States of America, Turkey, the European Commission and UNESCO have observer status.

lundi 13 août 2012

This Olympics has been watched from all over the world – and beyond. Benefiting from a cloudless sky, this view of London’s Olympic Park was captured by the smallest imager aboard ESA’s smallest mission: the High Resolution Camera on the Proba-1 microsatellite.

The Olympic Park, dominated by the circular Olympic Stadium, is visible towards the base of this 5 m-resolution image, with Victoria Park to its west and Hackney Marsh to the northwest.

This image was acquired by the High Resolution Camera (HRC). This black and white digital camera incorporates a Cassegrain telescope miniaturised to fit aboard Proba-1. Orbiting Earth at 720 km altitude, the entire satellite’s volume is less than a cubic metre.

HRC operates alongside Proba-1’s larger CHRIS (Compact High Resolution Imaging Spectrometer) hyperspectral imager, which takes 15 m-resolution scenes across a programmable selection of up to 62 spectral bands, from a variety of viewing angles. This HRC image was acquired on 11 August.

About Proba-1

Operational for more than a decade, Proba-1 was the first in ESA’s series of satellites aimed at providing in-orbit testing of new space technologies. Smaller than a cubic metre, Proba-1’s many experiments include the compact HRC that acquires monochromatic images with an area of 25 sq km.

Proba-1

Proba stands for ‘Project for Onboard Autonomy’ – both cameras are largely autonomous. Controllers at ESA’s Redu station in Belgium send up the location to be imaged – latitude, longitude and altitude – then the satellite itself does the rest, lining up its instruments with its target on the ground.

Proba-1 was launched in October 2001 as an experimental mission but is still going strong, having since been reassigned to ESA’s Earth observation team. This year a software fix returned its radiation-damaged star trackers to full operations.

In November 2009 Proba-1 was joined in orbit by Proba-2, focused on solar monitoring. Proba-V, to monitor global vegetation, is due to launch next year.